/*

 * Copyright (c) 2009, 2016, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package org.graalvm.compiler.nodes.java;

import static org.graalvm.compiler.nodeinfo.NodeCycles.CYCLES_64;

import static org.graalvm.compiler.nodeinfo.NodeSize.SIZE_64;

import org.graalvm.compiler.graph.IterableNodeType;

import org.graalvm.compiler.graph.NodeClass;

import org.graalvm.compiler.nodeinfo.NodeInfo;

import org.graalvm.compiler.nodes.ValueNode;

import org.graalvm.compiler.nodes.extended.MonitorExit;

import org.graalvm.compiler.nodes.memory.MemoryCheckpoint;

import org.graalvm.compiler.nodes.spi.Lowerable;

import org.graalvm.compiler.nodes.spi.LoweringTool;

import org.graalvm.compiler.nodes.spi.Virtualizable;

import org.graalvm.compiler.nodes.spi.VirtualizerTool;

import org.graalvm.compiler.nodes.virtual.VirtualObjectNode;

import org.graalvm.word.LocationIdentity;

/**

 * The {@code MonitorExitNode} represents a monitor release. If it is the release of the monitor of

 * a synchronized method, then the return value of the method will be referenced via the edge

 * {@link #escapedReturnValue}, so that it will be materialized before releasing the monitor.

 */

@NodeInfo(cycles = CYCLES_64, size = SIZE_64)

public final class MonitorExitNode extends AccessMonitorNode implements Virtualizable, Lowerable, IterableNodeType, MonitorExit, MemoryCheckpoint.Single {

    public static final NodeClass<MonitorExitNode> TYPE = NodeClass.create(MonitorExitNode.class);

    /**

     * Non-null for the monitor exit introduced due to a synchronized root method and null in all

     * other cases.

     */

    @OptionalInput ValueNode escapedReturnValue;

    public MonitorExitNode(ValueNode object, MonitorIdNode monitorId, ValueNode escapedReturnValue) {

        super(TYPE, object, monitorId);

        this.escapedReturnValue = escapedReturnValue;

    }

    /**

     * Return value is cleared when a synchronized method graph is inlined.

     */

    public void clearEscapedReturnValue() {

        updateUsages(escapedReturnValue, null);

        this.escapedReturnValue = null;

    }

    @Override

    public LocationIdentity getLocationIdentity() {

        return LocationIdentity.any();

    }

    @Override

    public void lower(LoweringTool tool) {

        tool.getLowerer().lower(this, tool);

    }

    @Override

    public void virtualize(VirtualizerTool tool) {

        ValueNode alias = tool.getAlias(object());

        if (alias instanceof VirtualObjectNode) {

            VirtualObjectNode virtual = (VirtualObjectNode) alias;

            if (virtual.hasIdentity()) {

                MonitorIdNode removedLock = tool.removeLock(virtual);

                assert removedLock == getMonitorId() : "mismatch at " + this + ": " + removedLock + " vs. " + getMonitorId();

                tool.delete();

            }

        }

    }

}